Grille insert for a vehicle bumper



FIG. 1 is a front view, showing my new design;

FIG. 2 is a left front perspective view thereof;

FIG. 3 is a right rear perspective view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof;

FIG. 7 is a bottom view thereof; and,

FIG. 8 is a rear view thereof. 

CLAIM The ornamental design for a grille insert for a vehicle bumper, as shown. 